Aerial photo taken on May 24, 2020 shows a tree-surrounded watch tower "Zhenbeitai" built in the Ming Dynasty (1368-1644), Yulin City, northwest China's Shaaxi Province. Friday marks China's National Tree Planting Day. With the efforts of volunteers across the country, green lands has covered more areas of China and the eco-friendly development concept is seeded in people's heart. (Xinhua/Tao Ming)